The Collaborative International Dictionary
Septennially
Septennially \Sep*ten"ni*al*ly\, adv. Once in seven years.
Wiktionary
septennially
adv. Once in every seven years.
Usage examples of "septennially".
Parliaments elected annually according to the Charter, so many points in which you have carried out, or triennially like the Australians, or septennially as in England of old?